This study is concerned with the practical optimum design of steel truss structures considering the minimization of the weight and the deflection using the H shape steel products made in the factories. The optimizing problems of truss structures are formulated with the objective functions and with the constraints which take the section areas as the design variables. The objective functions are formulated as either the total weight of the truss structure or the deflection of it according to the aims of users. The constraints are derived by using the criteria with respect to the tensile working stresses or the compressive stresses considering the buckle according to the kinds of steel member based on the part of steel bridge in the Korea standard code of road bridge, the deflection of truss structure and the upper and lower limit sectional area of each ember for the case of the weight minimization. The weight constraint is added to the previous constraint formulations for the case of the deflection minimization. The sectional properties of H shape steel are derived by using the correlationship equations obtained from regression analysis for the section modulli and the section areas, and the section inertia moments of seventy H shape steel products. The SUMT method using the modified Newton Raphson direction method is introduced to solve the nonlinear programming problems formulated in this study. The developed optimizing algorithm is tested out and examined throught the numerical examples for the optimum design and the practical design of a two tensile bars truss and a seven bars truss using the H shape steel products. And their results are compared and analyzed to examine the possibility of optimization, the applicablity and the convergency of this algorithm.

This study is to investigate the effects of carbon fiber and polymer on the fracture energy of cementitious materials. The volume contents of carbon fiber are 0.0, 0.5, 1.0, 1.5, and 2.0 percents and the content of polymer is 10 percents of the used cement weight. The three point bending tests were performed on all specimens with the initial notch (a/H=0.3). As results, the fracture energy of mortar increased as the contents of carbon fiber increased but were not so in concrete. And polymer contribute to the increment of fracture energy of CFRM. Therefore it can be drawn that the proper amounts of carbon fiber and polymer improve greatly the fracture energy and ductility of cementitious materials.

Dynamic analysis methods for building structures under subway transit loadings using the methods which includes soil-structure interaction effect in frequency and time domains are studied. An efficient substructure method is proposed using the dynamic stiffness matrix which have been evaluated by the direct method and equivalent transit loading along the soil-structure interface. The dynamic stiffness of soil is evaluated by the finite element method incorporating infinite elements for the radiational damping effect. In time domain analysis. frequency-independent stiffness and damping of soil are determined at a representative frequency. A mode superposition method equipped with the Gauss-Seidel iteration technique is employed. Example analysis is carried out for a building structure embedded into a layered soil medium.

In this paper, prediction techniques of maximum vehicle loadings and its effect on a highway bridge is investigated. A bridge structure is subject to a large number of truck load cycles or loading events during service lifetime. Each loading event consists of the effect of a truck or multiple trucks moving over the bridge. The loading event is characterized by the maximum moment in a bridge where the maximum moment is represented by the bridge influence line at a critical location. The probability distribution of the maximum moment (due to a single event) of a highway bridges under random truck loading is obtained by a convolution model. The model accounts for characteristics of a random truck such as axle weights, axle spacings and headway between trucks. Then, the moment distribution can be used to estimate the probability distribution of the maximum moment over the lifetime of the bridge structure. Finally, validity of the suggested model is verified by the sensitivity analysis for identifying important parameter involved in the maximum moment.

This paper presents the procedure and results of field tests that were performed on two steel I-girder bridges to assess girder distribution and impact factors. Specifically, the paper covers (1) test loads and a data acquisition technique, (2) a method of filtering dynamic strains, and (3) comparisons of measured girder distribution and impact factors with values calculated by the AASHTO methods. A major source of test loads applied on bridges was truck traffic moving at highway speeds. Strain data necessary to calculate girder distribution and impact factors were taken from bottom-flanges of girders in the middle of a span. A computerized data acquisition technique enabled selective recording of only the significant blocks of the strain data under normal traffic. Strains were measured for two consecutive days on each bridge. Measured data consist of selective strain blocks from approximately 900 trucks. The data were filtered with a lowpass digital filter to remove the dynamic components and to obtain an equivalent static strain. The data were further processed to obtain girder distribution and impact factors, and their statistics were derived. These statistics allowed to make comparisons between the measured factors and values calculated using the AASHTO methods. The results indicate that measured girder distribution factors are consistently smaller than the calculated values. Impact factors for heavy trucks are well below those of the AASHTO specifications.

Flutter analysis procedures incorporating spatial interaction of wind and structure are presented. Doublet point method(DPM) based on the three dimensional aerodynamic theory is employed for computing the unsteady aerodynamic forces, and structural model is composed by finite element method(FEM). The aeroelastic equation of motion is obtained by combining DPM and FEM. Complex eigenvalue problems are solved by iterative p-K method. The postulation that the wind flow can be assumed as two dimensional is shown to be no longer valid for the structures with low aspect ratio or free tip. Therefore flutter analysis based on the three dimensional aerodynamic theory is recommended for the structures mentioned above.

Due to the increasing traffic volumes and heavy loaded trucks, the quite heavy loads are acting on highway bridges. Therefore, it is important to evaluate lifetime maximum load effects and safety levels inherent in current design practice. In this studdy, lifetime extreme load effects are simulated for various bridge systems and traffic conditions. Based on the results, it is found that the current design practice does not guarantee consistent safety levels for the range of common effective span lengths. It is also shown that the simulated results are quite sensitive to both structural systems and traffic conditions, such as girder spacing, number of lanes, heavy vehicle composition, etc.

In this paper. an analytical method for determining the vibration of track due to train running is studied. The dynamic force transmitting to substructure through the track system is evaluated using the poposed method. The vertical load subjected to rail consists of the moving axle load and the roughness load mainly. The moving axle load is given by weight of train and the roughness load is induced by wheel and rail surface irregularities The solution procedures are introduced for those two load components separately. The continuous support model is adopted in this study Then the equation of motion is solved by applying the fourier integral method. Numerical analyses are carried out to examine the vibration of the ballast track generated by TGV train with speed. Also the chacteristics of the dynamic force generating the vibration of substructure is investigated.

In Prestressed Concrete structures, prestressing is used for artificially compensating the tensile stress, and then prestressing forces are decreased by many kinds of prestressing losses. Because friction loss among the losses of the prestressing varies with length of tendon and construction accuracy, it is very difficult to measure the exact prestressing force on the site. In this paper, tendency of friction loss will be investigated, and it will be found what kind of relationship between the specification and the site is, through measurement of friction loss coefficient and the determination of appropriate initial prestressing force by PRESTRESSING CONTROL SYSTEM. The results from this study can be summarized as follows. Recommended jacking force should be approximately 5% lower than specified prestressing upper limit. The specified control limit for curvature friction coefficient of PRESTRESSING CONTROL SYSTEM is about 0.25 and wobble friction coefficient 0.005. Thus, the control limit should be modified according to changed value of friction coefficient. It will be found that friction loss is more sensitive to wobble friction coefficient than curvature friction coefficient.

Laminated plates among the various structural forms using composite materials have been generally used and it is difficult to apply classical theory to these anisotropic materials because there exist stretching-shearing, bending-shearing, stretching-twisting, bending-twisting coupling. But these coupling effect can be diminished by proper stacking sequences and fiber orientations. Therefore, in this paper, the investigation calculation of stiffness matrix about laminated plates with various stacking sequences and orientations is conducted and the type of laminated plate to which coupling effects can be neglected is presented.

In the seismic design of nuclear power plant, it is very important in verifying the structural integrity to evaluate the seismic response and ultimate strength of the shear wall which acts as the primary lateral load resisting system. For this object, the ultimate seismic response tea for large scale reinforced concrete shear wall models were carried out by Nuclear Power Engineering Corporation in Japan. In order to simulate the seismic response test results of the shear wall, we use the Three-Vertical-Line-Element Model as a macroscopic model. This model idealizes the shear wall as three vertical line elements connecting two rigid horizontal beams which represent top and bottom slab. And the three hysteresis models are used to describe the force-displacement relationships of the line element springs of the model, those are the simplified axial stiffness hysteresis model, the origin oriented hysteresis model and the axial stiffness hysteresis model. We analyze the RC shear wall by using a macroscopic nonlinear dynamic analysis program SINDAS with the mechanical and the hysteresis models and compare the analysis results with the test results. The comparisons show good agreements over the whole test range.

AS Korean Gross National Product (GNP) is expected to Grow annually at the rate of about 7.2% an annual growth rate, investment for construction will continue to be in demand for housing supply and social overhead capitals such as highways, airports, and harbors. However, Korean construction industry has many problems such as a unhealthy contract practice, low quality, enviornmental contamination, technologies, subcontracting system, outdated construction management system, manpower and material. A prediction for the 21st century constructoin market is made on the basis of three assumptions. Korean construction market size is estimated at trillion won in 2001, and trillion won in 2005.

Now a days, the productivity of Korean construction industy is decreasing because of dirty, dangerous and difficult conditions of construction sites, and ever increasing labor cost. In 1997, Korean construction market will be opened to foreign competitors. To solve the problem, the relationship between the construction and GDP, and the factors such as labor cost, working hours, working day, transition of the productivity are studied by interviewing construction workers in Sanbon-dong, Kunpo-dong, Inchun Bugai-dong and Nonhyun-dong. Factors such as personal characters, satisfaction for work factors. reason of absenteesm and turnover were also studied. To improve the productivity of construction works, some suggestions are made.